diff --git a/common/content/bookmarks.js b/common/content/bookmarks.js
index e60fbbe1..b4d728dd 100644
--- a/common/content/bookmarks.js
+++ b/common/content/bookmarks.js
@@ -529,7 +529,7 @@ var Bookmarks = Module("bookmarks", {
                         description: "The character encoding of the bookmark",
                         type: CommandOption.STRING,
                         completer: function (context) completion.charset(context),
-                        validator: Option.validateCompleter
+                        validator: io.bound.validateCharset
                     },
                     {
                         names: ["-id"],
diff --git a/common/modules/base.jsm b/common/modules/base.jsm
index e368811c..7d34390b 100644
--- a/common/modules/base.jsm
+++ b/common/modules/base.jsm
@@ -17,7 +17,7 @@ function module(url) {
 }
 
 var { XPCOMUtils } = module("resource://gre/modules/XPCOMUtils.jsm");
-var { OS, TextDecoder, TextEncoder } = module("resource://gre/modules/osfile.jsm");
+var { OS } = module("resource://gre/modules/osfile.jsm");
 try {
     var { ctypes } = module("resource://gre/modules/ctypes.jsm");
 }
@@ -748,9 +748,13 @@ function memoize(obj, key, getter) {
     }
 }
 
-let sandbox = Cu.Sandbox(Cc["@mozilla.org/systemprincipal;1"].createInstance());
+
+let sandbox = Cu.Sandbox(Cc["@mozilla.org/systemprincipal;1"].createInstance(),
+                         { wantGlobalProperties: ["TextDecoder", "TextEncoder"] });
 sandbox.__proto__ = this;
 
+var { TextEncoder, TextDecoder } = sandbox;
+
 /**
  * Updates an object with the properties of another object. Getters
  * and setters are copied as expected. Moreover, any function
diff --git a/common/modules/io.jsm b/common/modules/io.jsm
index b0466dc2..c1a28320 100644
--- a/common/modules/io.jsm
+++ b/common/modules/io.jsm
@@ -216,6 +216,28 @@ var IO = Module("io", {
         }
     }),
 
+    charsets: Class.Memoize(function () {
+        const BASE = "@mozilla.org/intl/unicode/decoder;1?charset=";
+        return [k.slice(BASE.length)
+                for (k of Object.keys(Cc))
+                if (k.startsWith(BASE))];
+    }),
+
+    charsetBundle: Class.Memoize(
+        () => services.stringBundle.createBundle("chrome://global/locale/charsetTitles.properties")),
+
+    charsetTitle: function charsetTitle(charset, default_=charset) {
+        try {
+            return this.charsetBundle.GetStringFromName(charset + ".title");
+        }
+        catch (e) {}
+        return default_;
+    },
+
+    validateCharset: function validateCharset(charset) {
+        new TextDecoder(charset);
+    },
+
     // TODO: there seems to be no way, short of a new component, to change
     // the process's CWD - see https://bugzilla.mozilla.org/show_bug.cgi?id=280953
     /**
@@ -942,16 +964,9 @@ unlet s:cpo_save
             context.anchored = false;
             context.keys = {
                 text: util.identity,
-                description: function (charset) {
-                    try {
-                        return services.charset.getCharsetTitle(charset);
-                    }
-                    catch (e) {
-                        return charset;
-                    }
-                }
+                description: charset => io.charsetTitle(charset),
             };
-            context.generate = () => iter(services.charset.getDecoderList());
+            context.completions = io.charsets;
         };
 
         completion.directory = function directory(context, full) {